National Grid ESO claims world first approach to inertia, awarding £328m in contracts

Five companies are to provide National Grid ESO with inertia without the need to simultaneously provide electricity in what it is claiming to be a world first.

The six-year contracts – worth £328 million – have been awarded to Drax, Statkraft, Triton, Rassau Grid Services (Welsh Power) and Uniper, with nine companies putting their hat in the ring.

All of the successful companies will be either modifying existing assets or building new assets to provide stability services, using less energy and enabling reduced carbon emissions, the ESO said.

Key among these services will be inertia, particularly prominent in light of the 9 August blackout.

Under the new approach, inertia will be provided without having to provide electricity, allowing more renewable generation to operate and ensuring system stability at lower costs, the ESO said.

In total the contracts are procuring 12.5GVA seconds of inertia, which traditionally has been provided using the kinetic energy in the moving parts of large generators while they are providing electricity to the grid.

National Grid ESO accesses stability by calling on synchronous generators to run through the balancing mechanism, subsequently turning down non-synchronous generation.

However, this is an expensive process, with the ESO exploring whether there are more economic solutions available through the pathfinder tenders.

Having a large number of synchronous stations running at a low load also impinges on the ESO’s ability to access frequency and reserve services required for managing demand losses, it said.

The technology types the ESO accepted for the tender were synchronous compensators and synchronous generators running in a synchronous compensation mode.

The second phase of the Stability Pathfinder will facilitate a wider range of technology types, it said.

The ESO issued the invitation to tender for the Stability Pathfinder Phase 1 GB 2020, on 5th November 2019.

Julian Leslie, ESO head of networks, said lauded the approach as “the first of its kind anywhere in the world”.

“Our system is one of the most advanced in the world, both in terms of reliability and the levels of renewable power, and we’re really excited to be adding to that with this new approach to managing stability.

“These contracts are finding new ways to help balance the grid which are cheaper and greener, reducing emissions and saving consumers over £100m.”

Following the blackout in August, Ofgem’s report into the event recommended that the ESO come forward with recommendations to improve the transparency of real time operational requirements and its holding of reserve, response and system inertia.

Ofgem also said in its report that the ESO should also undertake a review, in consultation with the industry, into the SQSS requirements for holding reserve, response and system inertia.